"We are not talking about science fiction. We are talking about controlling sound waves by bending and twisting them in a designer space," said Fang

"Basically what you are looking at is an array of cavities that are connected by channels. The sound is going to propagate inside those channels, and the cavities are designed to slow the waves down," Fang said.

The researchers submerged the cylinder in a tank with an ultrasound source on one side and a sensor array on the other, then placed the cylinder inside the cloak and watched it disappear from their sonar.

"The structure of what you're trying to hide doesn't matter. The effect is similar. After we placed the cloaked structure around the object we wanted to hide, the scattering or shadow effect was greatly reduced," Fang said.

One problem plaguing fast-moving underwater objects is cavitation, or the formation and implosion of bubbles. Fang believes that they could harness their cloak's abilities to balance energy in cavitation-causing areas, such as the vortex around a propeller.

Next, the researchers plan to explore how the cloaking technology could influence applications from military stealth to soundproofing to health care.